Energy-transfer controlled dual-wavelength visible laser generation based on parallel nonlinear frequency up-conversions

Abstract

A compact frequency up-conversion scheme is demonstrated for dual-wavelength visible laser generation. The parallel sum-frequency generation (SFG) and second-harmonic generation (SHG) processes are simultaneously phase-matched and integrated in a well-designed periodically poled MgO:LiNbO3 crystal. Concurrent nonlinear up-conversions of the coupled SFG and SHG are thus realized. In the proof-of-principle experiment, two near-IR lasers at wavelengths of 800 nm and 1180 nm were used as independent fundamental beams. As a result, the generation of blue light at ∼477 nm by SFG (800 nm + 1180 nm → 477 nm) and the orange light at ∼590 nm by SHG of 1180 nm (1180 nm + 1180 nm → 590 nm) was simultaneously achieved. Finally, it is proved the relative strength of these two coupled nonlinear interactions and consequently the relative power of the blue and orange light could be freely controlled by changing the pump intensities of the fundamental beams, and a maximum photon conversion efficiency (∼25%) comparable to that of the separated SHG process was observed for this simultaneous dual-up-conversion device. This result provides a promising strategy for developing high-efficiency multi-wavelength visible laser systems. Combined with an engineered QPM crystal with different poling periods in sequence, more prospective nonlinear applications may be realized based a series of cascaded single- and dual-QPM nonlinear processes.